The Royal Flying Doctor's Service is regarded as a an Aussie Icon. It's nationally (and some will say internationally) famous, in part because it's the first kind of its kind of service in the world. They serve a lot of people throughout the outback who otherwise would have limited or no access to medicial services.

They now services an area of more than 7,150,000 square kilometres - an area bigger than Western Europe! - and maintains 23 bases throughout the country and has 36 aircraft.

The headquarters is in Alice Springs, so you might want to check out the building. It has a museum to show and explain what they do, which is pretty cool. There's an AV presentation followed by a guided tour of the radio communication section.